Which carb?

[TGB350LeMans]

Hi!
I have a 1969 LeMans with a 350, wide ratio Muncie 4 speed, and a 2.78 rear gear. This is a street / touring car and I'm primarily interested in crisp throttle response and decent mileage.  The engine is basically stock (small valve / 9:1 compression) with dual exhaust but an aftermarket cam - 212 / 225, 450/450 and 112 LSA, installed 4 degrees advanced. It currently has a performer intake and a 750 "slayer" carb. It runs great, but is a little "thirsty".

 First, I have a 1969 factory Q-jet intake to install.

I have 4 q-jets to choose from: First is the 17057274, which I understand is great, but I think it has the larger primaries, and not sure if it's the right choice for a street 350. Second is a 17054938 (72-74 Olds?), and the third is a 7043340 Buick (also with large primaries?) The fourth is a 17056253 Olds (?).

I'm guessing the 17057274 is still best with the adjustable APT. This carb is clean, and my first thought was just to refresh it and run it, but after reading some of your blogs, wondering if the calibration will be way off, and I should dig deeper right from the start.

Thanks in advance!!   Tom B.

[omaha]

I guess if it were me I would choose either the 17056253 or the 17057274. Probably would lean more towards the 17057274 cause it would be the  Pontiac carb.  I could not find a number that matches the 7043340 so I don't know if that is wrong number or not. the 17054938 is ok but I think the first 2 would be a better choice. YES you can use the larger casting on a 350 with no problems at all and in this case would be preferable.

[TGB350LeMans]

Thanks for the info!  My bad, 7043340 is actually 7042240, which I understand is a 71 Buick stage 1 carb.  I ordered the book this am. so will read up over the weekend.

thanks again!

Tom B.

[Ethan1]

 I would also go with carb 17057274.

[TGB350LeMans]

OK, after browsing through the book and re-looking at what I have, I really like this earlier style carb that I have, but it is  confusing the heck out of me. It is stamped 17054938,  which suggests a 1976-up "Mod Quad", but it is definitely the earlier (1969-75) style without the adjustable apt and the build date is "3110". It is a front inlet, like a Pontiac. It is also clean, and the primary throttle shaft has absolutely no slop (low miles?). From what I can find on a google search, it shows 1972-74 Oldsmobile... I plan on using recipe 1, and I guess as long as I size the idle restrictors and air bleeds per the recipe, the rest shouldn't matter much.
Do you have any idea what this actually came off of?
 I will be calling in for a kit as well, but wanted to solve the P/N vs "style" mystery first.
Thanks much!! I am enjoying the book!!
Tom B.

[Ethan1]

OK, after browsing through the book and re-looking at what I have, I really like this earlier style carb that I have, but it is  confusing the heck out of me. It is stamped 17054938,  which suggests a 1976-up "Mod Quad", but it is definitely the earlier (1969-75) style without the adjustable apt and the build date is "3110". It is a front inlet, like a Pontiac. It is also clean, and the primary throttle shaft has absolutely no slop (low miles?). From what I can find on a google search, it shows 1972-74 Oldsmobile... I plan on using recipe 1, and I guess as long as I size the idle restrictors and air bleeds per the recipe, the rest shouldn't matter much.
Do you have any idea what this actually came off of?
 I will be calling in for a kit as well, but wanted to solve the P/N vs "style" mystery first.
Thanks much!! I am enjoying the book!!
Tom B.

 Carburetor 17054938 is a Service Replacement for '73 Olds Cutlass A/T 350cid Rocket. The 3110 is 311th day of 1980. Service Replacements are usually not good carburetors to do a fresh build on.

 Stock specs of this carb were, .069" Primary Jets, 53C Primary Metering Rods, "K" Secondary Hanger and CG Secondary Metering Rods.

[Ethan1]

 For reference, 7043250 is what was replaced by the 17054938.

[Ethan1]

Hi!
I have a 1969 LeMans with a 350, wide ratio Muncie 4 speed, and a 2.78 rear gear. This is a street / touring car and I'm primarily interested in crisp throttle response and decent mileage.  The engine is basically stock (small valve / 9:1 compression) with dual exhaust but an aftermarket cam - 212 / 225, 450/450 and 112 LSA, installed 4 degrees advanced. It currently has a performer intake and a 750 "slayer" carb. It runs great, but is a little "thirsty".

 First, I have a 1969 factory Q-jet intake to install.

I have 4 q-jets to choose from: First is the 17057274, which I understand is great, but I think it has the larger primaries, and not sure if it's the right choice for a street 350. Second is a 17054938 (72-74 Olds?), and the third is a 7043340 Buick (also with large primaries?) The fourth is a 17056253 Olds (?).

I'm guessing the 17057274 is still best with the adjustable APT. This carb is clean, and my first thought was just to refresh it and run it, but after reading some of your blogs, wondering if the calibration will be way off, and I should dig deeper right from the start.

Thanks in advance!!   Tom B.

 Also, carb 17056253 was stock on the '76 Olds Cutlass and Delta A/T, A/C, Federal 350cid. And the 17057274 is the larger primary bores as well. Sorry for the multiple post.

[TGB350LeMans]

Ethan,

Thanks much! Mystery solved! .. OK, nix that carb. I found it also has the early short-fulcrum float - not good. I will go with the 17057274.. Also found out the 7042240 that I have appears to be for a 71 Buick 455 stage 1, large bore. This carb is pretty rough though, but complete - I think it will become Craigslist fodder or advertise to the Pure Stock Drag guys. . Sorry for all of the waffling.. I appreciate, and respect, your input...

thanks once again!!!

Tom B.

[Ethan1]

 Glad I could help. Cliff will know what kit/parts you will need, to work well with the specs of your car.

[Cliff Ruggles]

+3 or 4 on the 17057274, same carb used here:

http://www.youtube.com/watch?v=6zVdoLR-VzM

It will need a kit and slight tuning change for what you are doing.  When you get time, call the shop and we'll get what you need headed your way.

Also make sure that you account for the large front vent, it requires a matching hole in the air cleaner base, and must be sealed up as it's inside the filter area......Cliff